In the island divertor of the W7-AS stellarator a high-density zone (HDZ) near the divertor plates was discovered some years ago (Ramasubramanian et al 2004 Nucl. Fusion44 992–8) with electron densities up to 7 × 1020 m−3. We shed further light on this phenomenon by determining the poloidal and radial location of this zone and discussing potential implications of these findings. The HDZ is in the vicinity of, but clearly separated from the nearest X-point line. The carbon emission is clearly spatially separated, residing near or at the X-point lines. The HDZ shows many similarities with the hydrogen or wall MARFE in Textor-94 (Samm et al 1999 J. Nucl. Mater.266–269 666). The structure is associated with a strongly increased neutral pressure, thus enabling efficient pumping. This offers the possibility for a very efficient exhaust regime in a stellarator with island divertor such as W7-X, simultaneously with significantly reduced convective heat loads onto the divertor itself. The spatial separation of the HDZ and the carbon radiation region may imply that such a state can be reached even in a non-carbon machine, and might therefore be DEMO-relevant.